The objectives of this proposed research is: 1. To isolate and purify carcinoembryonic antigens and tumor-related antigens from human prostatic cancer tissue. 2. To study the immunological, chemical and physical properties of these purified carcino-fetal antigens. 3. To develop, improve and standardize the radioimmunoassay for tumor antigens in blood and urine of prostate cancer patients. 4. To investigate the usefulness of tumor antigen assay as a marker of response to treatment and of monitoring the recurrence of disease in prostatic cancers by long-term serial follow-up of patients.